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Cracked Block

B

bogdenz

Regular Contributor
"Hi all - I'm a first-time

"Hi all - I'm a first-time poster but have been utalizing this board for a while now. I've reached a point where a simple archive search probably won't give me the info/advice I need. Sorry if this is a bit wordy.....

Last year, I acquired a 1970 Buehler Turbocraft jet boat. The boat had seen very little action in it's lifetime and was all-original....including 318. Before I even put the boat in the water, I replaced the metal gas tank (varnished gas and all), copper fuel lines and fuel pump. I then ran it for one weekend in Sept. Knowing that would probably be my last usage of the season, I winterized it.....believing to have followed proper procedures. I didn't go crazy knowing it was going to be kept in climate-controlled storage starting in late Nov.

Unfortunately, we had an early freeze before it went to storage and, to my surprise, I blew a couple of freeze plugs. In addition to being surprised that the coolant hadn't found it's way throughout the block, I discovered that most of what had blown them out was frozen sediment/lake sand (maybe that's why the coolant didn't make it throughout).

I went through the winter keeping my fingers crossed that the plugs popping had saved the block. Today, I put in the new plugs and fresh oil and filter. She fired up right away and ran very smoothly (on the hose). After about 30 seconds of running, I shut it down and pulled the dipstick.....the fresh oil was now fresh milk. So, after the long intro, here's where I need some advice......

Short of a teardown, is there a way to determine, for sure, that it's the block (vs. a head gasket, etc., etc.) or....under the circumstances of the plugs popping, do I spare myself the time, effort and cost of trial and error and go right for a new block?

Note that, pre-winterization, oil was uncontaminated and compression was good in all 8.

Ultimately, now that we're in mid-June, I'm trying to prevent myself from my standard MO....which would be to take the long road to solving the problem.

Thanks in advance for reading....and for any and all advice.

Greg"
 
""Freeze Plugs" are no

""Freeze Plugs" are not well named. They are not there to save a block from cracking if frozen. The holes that the plugs fill are there to get the sand-casting patern (the pattern that forms the cooling passages) out of the block, during the casting process. The plugs are then installed to seal up those holes after casting. They can't really save a block from cracking.
A compression check should diagnose a blown head gasket. A cracked block will often keep putting water in the oil, sending the oil level higher and higher, eventually spilling out of several places. (like the dipstick tube)"
 
"Thanks Larry. I realize that

"Thanks Larry. I realize that “freeze plugs” is a bit of a misnomer……my hope was that they may have served the unintended purpose of relieving some of the pressure during the freeze. Given the time of year (mid Nov), the temps barely hit freezing and it would have been a rather slow freeze. Once I discovered the plugs had popped, I left a space heater in the boat for hours and thawed out anything that was left in the block.

You bring up a good point about the oil level. I immediately pumped out the milky oil and the extracted amount didn't seem to be any more than standard oil capacity.

I’d love to think that this could be a case of condensation. Since I ran the boat for less than a minute (on a garden hose only), it would seem as though I’d need a pretty drastically cracked block to milk-up the oil in such a short period of time……but I’m sure I could be wrong about that."
 
"No matter what you do with th

"No matter what you do with that engine it will at least cost you time.

I'd start with a compression test. If you find a low one, lock that cylinder at TDC. Attach a compressed air line to the plug hole. Listen for air blowing into the cooling system or grankcase at an extreme rate. That "may" be a head gasket.
Never the less, the water jacket is pretty thin in the valley. That is likely where a cracked block will show up.
Either a gasket or a crack, your pulling the intake to fix."
 
"Would a crack in the valley b

"Would a crack in the valley be visible once the intake was off?

Given how briefly I ran the engine (30-45 seconds maybe?), is it unusual that a cracked block or head gasket would allow the water to infiltrate the fresh oil so quickly? I ask with the thought process that…….unless an enormous crack, you’d assume it would occur with a bit more expansion/contraction. It ran so briefly that I could have rested my hand on the exhaust manifold after shut down.

In any event, I’ll probably start with the compression check and follow your advice from there.

Thanks"
 
""Would a crack in the val

""Would a crack in the valley be visible once the intake was off?"

Sometimes they are very easy to see. Others can be elusive. Look for a rust line if its minute.

"is it unusual that a cracked block or head gasket would allow the water to infiltrate the fresh oil so quickly?"

No, your pump is forcing the coolant throughout the engine trying to cool it. If it has an open, the coolant will tend to follow the path of least resistance. So, with thermostat closed during warmup its looking for somewhere to go.

Did you notice if your engine was blowing white smoke or steam out the exhaust?
If you take the intake off make sure you examine the gaskets and the intake bottom and ports for signs of water leaks."
 
"Thanks for the response(s

"Thanks for the response(s) Dave.

The exhasust looked good....in terms of having no smoke or steam. For a first-firing, the engine actually ran very well.

Reading your post about the t-stat also makes me realize an obvious mistake I may have made during winterization. Despire the fact that I ran the RV coolant through it until it came out the exhaust, it may not have ever reached a temp high enough to open the t-stat....explaining why the block had raw water in it.

I think I'm bumming. I'm going to throw some new oil in it tonight, run it and watch the "oil" level. If it rises, I'll probably go right after a long block crate motor. Otherwise, I'll tinker all season and still spend more than I would on a new motor."
 
"Sorry, but the block is crack

"Sorry, but the block is cracked (under the intake manifold). A rebuilt long block is your best choise.

Jeff"
 
I figured this would be the co

I figured this would be the conclusion. Thanks Jeff.

Any recommendations for a reputable source for the long block and anything specific to pay attention to when ordering (other than rotation)?
 
"Unfortunately for me, you guy

"Unfortunately for me, you guys were dead on. HUGE crack below the intake manifold. Adding insult to injury, it appears as though the motor has a very fresh rebuild on it....rockers, springs, rods, lifters, cam, etc. all appear brand new.

Thanks for the advice. You saved me some time for sure."
 
"In this case, I hate it when

"In this case, I hate it when you're right too!

Thanks again....and for the referral as well. I'll give these guys a buzz tomorrow. I also found a place that's somewhat local to me (1800runsnew.com). If anyone's dealt with them, feedback would be appreciated. Local would be nice as I could save some shipping $$$ in addition to having them close by in the event of a warranty issue."
 
"We used to offer reman long b

"We used to offer reman long blocks and beat that price at marine powersource easily. Plus we had free shipping. If your really interested in one drop me a line and I will check out the current prices and work up a quote.

Dave
[email protected]"
 
"I bought a 318 long block fro

"I bought a 318 long block from 1800runsnew in Holiston, MA in 2004. I got good service & competitive prices. The driver who delivered the engine used the gatelift on his truck to help me mount it on my engine stand before he left. He didn't just drop the pallet on the garage floor and leave. Their prices were competitive on a velvet drive transmission & exhaust manifolds. They also don't require a core exchange for most engines which allowed me to undress the engine at my own pace, which is a lot than stripping the old block for immediate return and trying to remember exactly how everything fits. I give them thumbs up."
 
"Chuck, I’m really glad you po

"Chuck, I’m really glad you posted. As I mentioned to Dave Kain this morning (who, BTW, has been very generous in helping to hook me up with a reputable vendor back-up vendor), I’m very close to pulling the trigger with 1800runsnew because they’re fairly local and I like the idea of having the accountable party within driving distance if an issue arises. I had long conversation with the owner last night and got a good vibe. That said, I had a good vibe about the way I winterized my engine last year! In other words, feedback from someone who’s used them is much better than my "vibe". I appreciate it.

Thanks again. I’ll keep you guys posted.

Greg"
 
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